Note: Descriptions are shown in the official language in which they were submitted.
CA 02448892 2003-11-12
[Description]
[Tile of the Invention]
ELECTROLYTE SOLUTION FOR MANUFACTURING
ELECTROLYTIC COPPER FOIL AND ELECTROLYTIC COPPER FOIL
MANUFACTURING METHOD USING THE SAME
[Detailed Description of the Invention]
[Field of the Invention]
[Background of the Invention]
The present invention generally relates to an electrolyte solution
used to manufacture an electrolytic copper foil fo:r a printed circuit and an
electrolytic copper foil for an electrode collector of a secondary battery,
the
electrolytic copper foil using the same, and an electrolytic copper foil
manufacturing method thereof.
A printed circuit board using the electrolytic copper foil is widely
used as a precise control circuit of various electric, electronic
communication apparatuses such as radios, TVs, computers, telephone
exchanges; wireless transceivers, etc. Recently, as a degree of integration of
the printed circuit board increases, circuits of the board get minute and
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CA 02448892 2003-11-12
multilayered. Particularly, the electrolytic copper foil is highly demanded in
terms of COF(Chip On Flex) and TAB(Tape Automatic Bonding) aspects,
and is broadly used as an electrode collector of a secondary battery by
improving its physical properties.
Generally, the electrolytic copper foil is created by electrolytic
methods, and is manufactured from a cylinder-shalaed cathode(also, called a
drum) consisting of titanium, an anode consisting of a lead alloy keeping
certain intervals or titanium covered by an iridium oxide, and an electrolytic
cell including an electrolyte solution and current power. The electrolyte
solution is composed of sulfuric acid and/or a copper sulfate. When DC
flows between the cathode and the anode as rotating the cylinder-shaped
cathode, copper is electrodeposited on the cathode, thereby consecutively
producing the electrolytic copper foil. Thus, a process of restoring a copper
ion to metal with the electrolytic methods is called a thin film process.
Next, when necessary, to improve an adhesive force with an
insulating substrate, the copper foil obtained from the thin film process can
pass through additional surface treatment processes including a roughness
treatment process(also, called a nodule treatment process), a
nonproliferation process to prevent the copper ion from being proliferated,
an anticorrosive process to prevent oxidation fi°om outside, a chemical
adhesive force improving process to complement an adhesive force with the
insulating substrate, and so on. If passing through the surface treatment
process, the copper foil is made for a low profile printed circuit. And, if
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only an anticorrosive process of the surface treatment process is performed,
the copper foil is made for the secondary battery.
In case the electrodeposited copper foil is used for the printed circuit,
the copper foil is supplied to a PCB(Printed Circuit Board) process
manufacturer while being adhered(laminated) to the insulating substrate
after the surface treatment process. However, if used for the secondary
battery, the copper foil is supplied to a secondary battery manufacturer via
the anticorrosive process only.
For the copper foil appropriate for a minute and highly integrated
PCB circuit, the surface of the copper foil contacted with the insulating
substrate should have a small roughness. In addition, while coupling the
electrolytic copper foil with the insulating substrate, if the copper foil
gets
stress by thermal expansion or heat-shrink and moreover, the copper foil is
laminated in multilayer way, it may have scratches due to friction with a
neighboring copper foil. More seriously, the copper foil can be exfoliated
from the insulating substrate or have circuit damage, or a PCB may get bent
or distorted. To protect the copper foil from these problems, it is necessary
to have a proper elongation without suddenly deteriorating mechanical
intensity at high temperature. When the electrolytic copper foil is used as
the collector for the secondary battery, electrode materials should cover
both sides of the copper foil. In this case, if both sides of the electrolytic
copper foil have a different roughness, battery characteristics differ from
each side. Therefore, it is required to have the same or a similar roughness
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on both sides of the electrolytic copper foil. Furthermore, to reduce weight
and a manufacturing cost of the battery and increase energy density of the
battery, the electrolytic copper foil should be manufactured in thin type.
Even though the copper foil is thin, it is necessary to have sufficient
mechanical intensity and an elongation at high temperature, without being
bent in a future treatment process.
To satisfy the above requirements, the prior art has suggested a
method of making an electrolytic copper foil b;y adding various organic
additives to an electrolyte solution. As a representative example, the United
States Patent No. 5,431,803 has been suggested to lower a surface
roughness, providing a method of manufacturing an electrolytic copper foil
that maintains concentration of a chlorine ion less than lmg in a 1-liter
electrolyte solution. However, the electrolytic copper foil manufactured by
a technology suggested in the United States Patent No. 5,431,803 has
6lkgf/mm2 to 84kgf/mm2 of mechanical intensity at room temperature as well
as l 7kgf/mt~ to 25kgf/mi~ at 180 °C , and has about Gum of the maximum
value of the surface roughness:Rmax for a surface treatment. Thus, it is not
appropriate for the secondary battery Also, it is difficult to carry out a
consecutive operation as maintaining the concentration of the chlorine ion
less than lmg in the electrolyte solution.
[Summary of the Invention)
It is therefore an object of the present invention to provide an
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electrolyte solution for a printed circuit, an electrolytic copper foil
produced
using the same, and a manufacturing method 'thereof for controlling a
roughness on both sides of the electrolytic copper foil in the same or
.similar
way according to electrolyte solution additives and for preventing sudden
intensity changes even at high temperature compared to room temperature
by controlling the amount of the electrolyte solution additives.
It is another object of the present invention to provide an electrolyte
solution used to manufacture an electrolytic copper foil, the electrolytic
copper foil produced using the same, and an electrolytic copper foil
manufacturing method thereof for having a roughness I~z value of a rough
surface is less than 2.O~cm in a thin film state and for preventing sudden
intensity changes even at high temperature compared to room temperature.
(Detailed Description of the Preferred Embodiment]
To accomplish the above objects, as an electrolyte solution for
manufacturing an electrolytic copper foil, the present invention provides the
electrolyte solution, the electrolytic copper foil produced by using the
electrolyte solution, and an electrolytic copper foil manufacturing method
thereof. . In an electrolyte solution containing at least selected one of
sulfuric acid and copper sulfate used to manufacture an electrolytic copper
foil by electrolysis, the electrolyte solution for manufacturing the
electrolytic copper foil, based on the 1-liter electrolyte solution,
comprising:
0.5 to 40mg of at least one sulfur compound selected from a disulfur
compound, diaklyamino- T oxomethyl- thioalkan sulfonic acid, and
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thioalkan sulfonic acid salt; 1 to 1000mg of at least more than one kind of
an organic compound selected from a group consisting of a poly aklylene
glycol-type surfactant and low molecular gelatin; and 0.l to 80mg of
chlorine ion added.
A solution comprising i) sulfuric acid and copper salt rather than
copper sulfate, or ii) copper sulfate and acid rather than sulfuric acid may
be also used as the electrolyte.
The organic compound comprising low molecular gelatin without
polyalkylene gulycol type surfactant may be also used as the organic
compound.
Generally, a process of manufacturing an electrolytic copper foil for
a printed circuit is divided into a thin film process and a surface treatment
process.
The thin film process is generally performed by using an
electroforming cell. Within an electrolytic cell, a semi-cylinder type anode
and a cylinder-type rotating cathode are located at certain intervals, and the
electrolyte solution is consecutively supplied between the anode and the
cathode. By flowing DC between the anode and the; cathode, a copper ion of
the electrolyte solution is restored to metal having predetermined thickness
from the cathode. Next, a copper foil (undisposed) that does not pass
through a future treatment process is exfoliated from the surface of the
cathode. A lead alloy is widely used for the anode, but recently, intervals
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are changed by corrosion of a lead oxide. Therefore, titanium covering an
iridium oxide is more used. The cathode is used by plating iron with
chromium, however recently, stainless materials are covered with titanium
to lengthen the span of life.
Next, to provide requested characteristics when necessary, an
additional treatment process of passing the undisposed copper foil through a
processor can be performed. This treatment process includes a roughness
treatment process to improve an adhesive force when laminated on an
insulating substrate, a nonproliferation process to prevent a copper ion from
being proliferated, and an anticorrosive process to prevent oxidation during
storage, transportation or a lamination forming process of the copper foil
and the insulating substrate. Hereinafter, the above processes will be more
fully described. The above processes are performed in the processor having
the anode, and a surface treatment copper foil is finally obtained through
these processes.
The electrolyte solution supplied between the anode and the cathode
is a copper sulfate solution, and its blending based on lliter is as follows:
Copper concentration is between 50g acid 110g, and desirably,
between 60g and 100g. Sulfuric acid concentration is between 80g and
200g, and desirably, between 90g and 120g. Temperature of the electrolyte
solution is between 40 °C and 80 °C . Current density is between
400A/cm2
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and 10000A/dm2, and desirably, between SOA/dm2 and 85A/dm2. If the
copper concentration is less than SOg, the surface of an electrodeposited
copper foil is rough and powder is formed, lowering productivity. However,
if more than 110g, the electrolyte solution is crystallized, deteriorating
working efficiency. If the sulfuric acid concentration is less than 80g, an
electrolytic voltage rises, resulting in an increase of production cost. Also,
temperature of the electrolyte solution rises, causing deterioration of
mechanical intensity of the copper foil. If the sulfuric acid concentration is
more than 200g, the electrolyte solution is highly apt to be corrosive even
though the electrolytic voltage lowers; thereby quickly corroding an
electrode electrolyzing the copper foil.
At this time, the electrolyte solution contains a sulfur compound
having 0.5 to 40mg of concentration and at least more than one kind of an
organic compound selected from a group consisting of a poly alkylene
glycol-type surfactant having 1 to 1000mg of concentration and low
molecular gelatin as additives. In addition, a chlorine ion having a range of
O.lmg to 80mg is added.
More desirably, to increase intensity of the electrolytic copper foil
produced by the electrolyte solution, it is possible to use a nitrogen
compound. For a thiourea derivative, which is the nitrogen compound,
IM(2-imidazolidinethione) is used within a range of 0.1 mg to 8 mg. As for
the poly alkylene glycol-type surfactant; it is available to use poly ethylene-
type, poly propylene-type, and poly butylenes-type surfactants. Particularly,
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poly ethylene glycol can be representative of the poly ethylene-type
surfactant.
A disulfur compound and diaklyamino- T-oxomethyl- thioalkan
sulfonic acid or thioalkan sulfonic acid salt are included in the sulfur
compound. The disulfur compound includes SPS(Bis-(3-SUlfopropyl)-
disulfide, disodium salt)), and diaklyamino- T-oxomethyl- thioalkan
sulfonic acid or salt thereof can contain dithiocarbamic acid or salt thereof,
and DPS(N, N-Dimethyldithiocarbamic acid (3-sulfopropyl), sodium salt) is
representative. A formula of the diaklyamino- T-oxomethyl- thioalkan
sulfonic acid or the salt thercof is shown in a chemical formula 1, and a
formula of the DSP as a representative example is shown in a chemical
formula 2, then a formula of the SPS is shown in a chemical formula 3.
Chemical formula 1,
R~~, S
~N-C-S ~CH2)ri$Q3X
R
'R' in the chemical formula 1 means an alkyl group(carbon atom
1~6), 'n' is 2 ~ 3 (ethane , propane), and 'X' means hydrogen atom or alkali
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metal atom.
(Chemical formula 2]
3 0,,
N-C-S CZ S~ X
wC~ wC~ 3
H2 H2
(Chemical formula 3]
S-CHI-CH2-CH2-S03Na
S
S-CH2-CHZ-CH2-S03Na
Among the above additives, the roles of the sulfur compound and the
surfactant are very important, since these compounds give direct influence
on a surface roughness and tensile strength. Compared to a general
electrolytic copper foil added with glue or gelatin, the sulfur compound
generally has a srr~all size of grains and functions as a grain refiner or a
brightened. The added surfactant functions as a carrier or an
electrodeposition leveler lowering a surface roughness of a mat surface of
the electrolytic copper foil, influencing electroposition. In this case, the
surfactant is absorbed into a protruded part of an electrode surface as
carrying the sulfur compound, which is a brightener, to a cathode surface,
and suppresses growth of the protruded part, thereby intemzpting the
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growth firstly. And the sulfur compound, which is the grain refiner, firstly
functions in a minute valley part of an electroposition surface, and enables a
copper ion to be restored and grow up in this part first of all, thereby
controlling a roughness of the electrodeposition surface.
The thiourea derivative, the nitrogen compound used in the present
invention suppresses crystal growth of copper at room temperature or high
temperature by eutectoid-processing nitrogen on an electrodeposition layer,
and also restrains strength deterioration. Thus, when the nitrogen compound,
the thiourea derivative is added, it is possible to prevent the strength
deterioration, which occurs otherwise. So, a defective proportion caused
when dealing with the electrolytic copper foil or manufacturing the printed
circuit can be reduced. Moreover, the strength can be chamged by
controlling an amount of the additives, thereby adjusting physical properties
of the electrolytic copper foil.
For the electrolytic copper foil in accordance with the present
invention, if it is undisposed, it seems that a roughness of a rough
surface(mat surface) has an Rz value having a range of 2.O~n.'RZ has been
measured by an IPC TM 650 2.2:17A method. For other copper foil passing
through surface treatment, it seems that the roughness of the rough
surface(mat surface) has an Rz value having a ran~;e of 1.0 ~ 3.S~m. Since a
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roughness value of a drum surface(bright surface) of the copper foil
contacted with the drum surface is produced accarding to polishing of the
drum surface, there is no particular restriction.
In order to improve an adhesive force with an insulating substrate, if
necessary, the above undisposed copper foil can pass through additional
surface treatment processes including a roughness treatment process(also,
called a nodule treatment process), a nonproliferation process to prevent a
copper ion from being proliferated, and an anticorrosive process to prevent
oxidation from outside. If passing through the surface treatment process, the
copper foil is made for a low profile printed circuit, however, if passing
through the anticorrosive process only, the copper foil is for a secondary
battery.
The roughness treatment process consists of two steps or three steps.
In a first step, a core of minute powder is made, and the powder is coupled
with the copper foil in a second step because the powder does not have an
adhesive force with the copper foil. In a third step, a minute protrusion is
given to the coupled powder again. The first step is as follows. Based on a
1-liter electrolyte solution, copper concentration is between lOg and 40g,
and desirably, between 15g and 25g. Sulfuric acid concentration is between
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40g and 1 SOg, and desirably between 60g and 1 OOg, and temperature of the
electrolyte solution is between 20 °C and 40 °C .
Current density is between 20A/dm2 and 1OOA/dm2, and desirably,
between 40AJdm2 and 80A/dm2. The second step is as follows: Copper
concentration is between SOg and 110g, and desirably, between SSg and
100g. Sulfuric acid concentration is between 80g and 200g, and desirably,
between 90g and 120g. Temperature of the electrolyte solution is between
40 ~ and 80 °C . Current density is between 20A~'dm2 and 1 OOAldm2, and
desirably, between 40A/dm2 and 80A/dm2. The nonproliferation process is
as follows. To prevent the copper ion from being proliferated, a barner layer
is formed with various single metal such as zinc, nickel; iron, cobalt,
molybdenum, tungsten, tin, indium, and chrome, or with 2 or 3 kinds of
alloys.
Then, to prevent oxidation during storage, transportation, or a
lamination forming process of the copper foil and the insulating substrate,
the anticorrosive process is carried out. The anticorrosive process performs
chromate passivation with chromic acid, sodium dichromate, potassium
dichromate, chromic anhydride, etc. Next, a process for increasing chemical
cohesion is executed.
Also, a chemical adhesive force improving process can be carried
out to complement an adhesive force with the insulating substrate. For this,
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there are usable adhesion accelerators such as a silane coupling
agent(RSiX3), silicon peroxygen(R4-nSi(OOR')n), a chromium-based
adhesion accelerator((RCO2H30HCrOHCrHOH2)20H), an organic
titanium based adhesion accelerator((C4H9CHC2HSCH20)4Ti), an organic
phosphate,based adhesion accelerator(R02P(OH)2), and others.
Embodiments
Hereinafter, the present invention will be described in reference to
the embodiments and compared examples. Here, a symbol 'g/L' means a
content of a corresponding material based on a 1-liter electrolyte solution.
For a thin film process, the electrolyte solution having blending like
described in Table 1 is prepared. Copper concentration of the electrolyte
solution is 80g/L, sulfuric acid concentration is 90g/L; and temperature of
the electrolyte solution is 45 °C . Additives like described in Table 1
have
been added. Current density was electrodeposited in 60A/dm2, and chlorine
ion was maintained in 25mg/L.
For embodiment l, 6mg/L of DPS(N, IV-Dimethyldihiocarbamic
acid(3-sulfopropyl) ester, sodium salt) was used as a sulfur compound, and
lmg/L of PEG(Poly Ethylene Glycol) was used as a poly alkylene glycol-
type surfactant.
For embodiment 2, lmg/L of SPS(Bis-(3-sulfopropyl)-disulfide,
disodium salt) was used as a sulfur compound, and 30mg/L of PEG(Poly
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Ethylene Glycol) was used as a poly alkylene glycol-type surfactant.
For embodiment 3, 30mg/L of DPS(N, N-Dirnethyldihiocarbamic
acid(3-sulfopropyl) ester, sodium salt) was used as a sulfur compound, and
30mglL of PEG(Poly Ethylene Glycol) was used as a poly alkylene glycol-
type surfactant.
For embodiment 4; Smg/L of SPS(Bis-(3-sulfopropyl)-disulfide,
di~odium salt) was used as a sulfur compound, and lmg/L of PEG(Poly
Ethylene Glycol) was used as a poly alkylene glycol-type surfactant.
For embodiment 5; 3mg/L of DPS(N, N-Dimethyldihiocarbamic
acid(3-sulfopropyl) ester, sodium salt) was used as a sulfur compound,
and 800mg/L of PPG(Poly Propylene Glycol) and Smg/L of low molecular
gelatin less than molecular weight 6000 were added as a poly ethylene
glycol surfactant.
For embodiment 6, Smg/L of SPS(Bis-(3-sulfopropyl)-disulfide,
disodium salt) was used as a sulfur compound, O.Smg/L of IM(2-
imidazolidinethione), which was a thiourea derivative, was as a nitrogen
compound, and 25mg/L of PEG(Poly Ethylene Glycol) was used as a poly
ethylene glycol-type surfactant.
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For embodiment 7, 3mg/L of SPS(Bis-(3-sulfopropyl)-disulfide,
diSodium salt) and Smg/L of DPS(N, N-Dimethyldihiocarbamic acid(3
sulfopropyl) ester, sodium salt) were as a sulfur compound, and 30mg/L of
PEG(Poly ethylene glycol) and 30mg/L of PPG(Poly Propylene Glycol)
were used as a poly ethylene glycol-type surfactant.
By using the electrolyte solution prepared like above, a titanium
anode covering an iridium oxide, and a rotating cylinder-type titanium
cathode, the undisposed copper foil corresponding to the embodiments 1 to
7 was obtained, respectively, under an electrolytic condition like described
in Table 1.
In case of the sulfur compound, an Rz value tended to exceed 2.Oum
by an increase of a surface roughness of a rough surface in a range of
exceeding 40mg/L. When used less than 0.5 mg/L, the surface roughness
did not lower, rather the roughness increased as lowering an elongation. As
for the poly ethylene glycol-type surfactant, it was possible to confirm a
function of lowering the surface roughness of the rough surface within a
range of lmg/L to lOOOmg/L. More desirably, a desirable surface roughness
could be obtained within a range of lmg/L to 300mg/L. However, in this
case, it was required to control using current density in higher or lower way
according to its amount. For the sulfur compound and the poly ethylene
glycol-type surfactant, if concentration was higher than an upper limit
above, the surface got rough and burning phenomenon (electrodeposited
into powder) occurred. Thus, they might not be usable for manufacturing a
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satisfactory electrolytic copper foil.
So as to control hardness of the manufactured electrolytic copper foil;
it was proper to have a range of O.lmg/L to 8mg/L for the nitrogen
compound additionally included to form the electrolyte solution. If an
amount of an additive was too little, the hardness got slightly improved; and
if too much, the hardness got higher but a surface roughness rose, thereby
lowering an elongation.
For each of the undisposed copper foil, a surface roughness Rz was
measured according to an IPC TM 650 2.2.17A method, and an elongation
and tensile strength of the copper foil have been measured at room
temperature(25 °C ) and 180 °C according to an IPC TM 650
standard
processing method, The results are shown in Table 2.
Next, a surface treatment process was carried out for the undisposed
copper foil in accordance with the embodiments 1 to 7. First, for a
nonproliferation process, 110g/L of sodium cyanide, 60g/L of sodium
hydroxide, 90g/L of copper cyanide, and 5.3g/L of zinc cyanide have been
electrodeposited with pH 11.0 to 11.5 at 50 °C, having SAldm2 of
current
density for 10 seconds. For an anticorrosive process, lOg/L of sodium
dichromate has been measured with pH 4.5, having 0.5A/dm2 of current
density for 2 seconds.
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Compared Examples
The composition of the electrolyte solution and the chlorine ion
concentration are the same as the above embodiments. For a compared
example 1, 2mg/L of low molecular gelatin less than 6000 molecular weight
has been added as an additive. For a compared example 2, 1mg/L of
TU(thiourea) has been added with 2mg/L of low molecular gelatin less than
6000 molecular weight. For a compared example 3, SOmg/L and 30mg/L of
SPS and PECK respectively, have been added. And for a compared example
4, 3mg/L and 1500mg/L of DPS and PPG, respectively, have been added.
Under the electrolytic condition described in Table l, the
undisposed copper foils corresponding to the compared examples 1 to 4
have been obtained, as well as a surface roughness Rz for the undisposed
copper foils, and an elongation and tensile strength were measured at room
temperature(25 °C ) and 180 °C by an IPC IM 650 2.4.18A method.
The
results are shown in Table 2. Next, a surface treatment process has been
carried out for the undisposed copper foils in accordance with the compared
examples 1 to 4.
Table 2 shows the results of comparing physical properties of the
copper foil tentatively manufactured through the embodiments and the
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compared examples under the condition suggested in Table 1.
Like displayed in Table 2, according to the embodiments in
accordance with the present invention, a roughness (Rz) of a rough surface
is controlled less than 2.0 by the sulfur compound. Thus, it is possible to
maintain similarly to a roughness (Rz) of a drum surface and change
strength by controlling an amount of the thiourea derivative, the nitrogen
compound, thereby enabling the electrolytic copper foil to be manufactured
for various purposes.
[Table 1]
Additives Solution
Com
osition
SPS DPS IM PEG ppG Low MolecularTU Cl- CopperSulfur
(mg/L)(mg/L)(mg/L)(mg~L)mglL)mia (mg~L)lm~ A
~'
L Ion /L
Embodiment - 6 - 1 - -
1
Embodiment 1 - - 30 - - -
Z
Embodiment - 30 - 30 - - -
3
Embodiment 5 - - 1 - - -
4
Embodiment - 3 - - 800 5 -
5
Embodiment 5 - 0.5 2S - - -
6
Embodiment 3 5 - 30 30 - - 2S 80 90
7
Compared - - - - - 2
Exam 1e 1
Compared - _ - _ - 2 1
Exam 1e 2
Compared 50 - - 30 -
Exam 1e 3
Compared - ~ ~ ~ ~ ~ - -
3 - - 1500
j Example
4
Current density: 60 Aldm2, Solution temperature: 4.5
DPS: N-Dimethyldithiocarbamic acid (3-sulfopropyl) ester, sodium salt
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SPS: Bis-(3-sulfoprapyl)-disulfide, disodium salt
IM: 2-imidazolidinethione
PEG: Poly Ethylene Glycol
PPG: Poly Propylene Glycol
Low molecular gelatin: gelatin less than 6000 molecular weight
TU: thiourea
[Table 2]
Surface Surface Tensile
ElongationTensile
Roughness of Roughness Iongatio
of Strength ~
Rough Drum (Room doom Strength(180
~)
Temperature)(180
C)
Surface Surface Tem erature
(Rz:um) Rz:;tmt) (k f/~t) (%) (k (%)
f/~
Embodiment1;52 1.68 33.2 8.9 22.5 7.6
1
Embodiment1,g3 1.76 29.5 9.6 20.9 8.0
2
Embodiment1,42 ~ 1.84 33.4 12.9 22.2 14.4
3
Embodiment1,88 1.91 30.4 12.9 20.6 10.6
4
Embodiment1,g1 1.79 31.4 4.1 18.4 3.1
g
Embodiment0,50 1.75 33:2 11.4 23.6 6.0
6
Embodiment1.14 1.55 32.0 8.8 20.6 4.2
7
Compared3,53 1.81 37.1 5.6 22.8 2.2
Exam
1e 1
Compared' 1.9 1.85 49.0 1.5 22.0 1.9
Exam
1e 2
Compared2,23 1.88 34.2 1.9 22.2 3.5
Exam
1e 3
Compared2,38 1.79 13.9 0.23 16.9 1.2
Exam
1e 4
Like shown in the embodiments 1 to 7 suggested in Table 2, the
electrolytic copper foil manufactured in the embodiments in accordance
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with the present invention has a surface roughness Rz value of a rough
surface within a range of 2.O~cm in a thin film state. It is also confirmed
that
tensile strength at room temperature is not rapidly changed even at high
temperature( 180 ~ ) as well.
[Results of the Invention]
An electrolytic copper foil in accordance with the present invention
has a roughness Rz value of a rough surface(mat surface) with a range of
less than 2.O~.ctn, if undisposed. However, if the copper foil passes through
a
surface treatment process, it has a roughness Rz value of a rough
surface(mat surface) within a range of 1.0 ~ 3.Sum. Therefore, the
electrolytic copper foil in accordance with the present invention has a
relatively lower roughness on the rough surface, and both sides of the
electrolytic copper foil have a similar roughness.
An electrolytic copper foil manufactured in prior art has a problem
of rapidly causing strength deterioration at high temperature( 180 °C
), though
good strength is maintained at room temperature. However, the electrolytic
copper foil in accordance with the present invention does not show any
sudden strength change even at high temperature. Accordingly, the
electrolytic copper foil in accordance with the present invention is
appropriate for a minute and highly integrated PCB circuit.
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Furthermore, when used as a collector for a secondary battery, a
more reliable battery characteristic can be obtained, since a roughness on
both sides of the electrolytic copper foil is similar. The electrolytic copper
foil in accordance with the present invention prevents tensile strength from
suddenly deteriorating owing to a temperature rise, having excellent
elongation characteristics at room temperature and high temperature. Thus,
it would not get bent or distorted in a future treatment process nor generate
a short circuit. The electrolytic copper foil in accordance with the present
invention is proper to be used as the collector for the secondary battery or a
printed circuit board.
It is to be understood that changes and madifications to the
embodiments described above will be apparent to those skilled in the art,
and are contemplated. It is therefore intended that the foregoing detailed
description be regarded as illustrative rather than limiting, and that it be
understood that it is the following claims, including all equivalents, that
are
intended to define the spirit and scope of this invention.
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